Controlling the condition of litter in poultry houses is essential to ensure a better environment and thus better health and performance of the birds. The condition or quality of litter can be affected by a number of factors such as moisture, temperature, pH, ventilation, stocking density and frequency of cleanout. Of these factors, cleaning out the built-up litter more frequently is the most effective way to control and immediately improve litter quality. Unfortunately, this method of improving litter quality is becoming less of an option for producers since litter costs have dramatically increased in recent years. Therefore, many producers have adopted the practice of reusing litter as a strategy to reduce costs. In broiler houses, litter will routinely be reused for four or more sequential flocks of birds. In turkey grow or finish houses, litter will be reused for two or more sequential flocks of birds. While the reuse of litter has reduced the immediate litter costs, the use of built-up litter necessitates implementing better management practices to maintain litter quality. Poor litter conditions lead to an increase in the populations of microbial pathogens in the litter and excessive ammonia production.
Ammonia is a noxious gas that is produced by the microbial decomposition of nitrogenous waste in the litter. The deleterious effects of ammonia on broiler performance, health and carcass quality have been well documented. The presence of ammonia is a major physiological stress agent which is directly related to the health of the bird. This results in lower weight gain and generally unhealthy birds. Mortality also increases. Prolonged ammonia exposure at concentrations higher than 25 ppm has been shown to denude the cillia of the trachea and leave the bird vulnerable to challenges from respiratory ailments common in commercial poultry houses. High concentrations of ammonia can also blind young chicks.
The ammonia present in broiler and other poultry housing facilities is the product of microbial decomposition of excreted nitrogenous compounds. These compounds consist primarily of uric acid and nonabsorbed proteins, amino acids, and nonprotein nitrogen present in the diet. Approximately 50% of nitrogen excreted by poultry is in the form of uric acid. The nitrogen is derived from the degradation of amino acids which are in excess of metabolic needs for protein synthesis. The carbon that remains is used for (1) glucose synthesis, (2) conversion into fat or (3) metabolized into energy, CO.sub.2 and H.sub.2 O. The remaining nitrogen is excreted in fecal matter.
While all of this excreted nitrogen is readily biodegradable, uric acid is the most rapidly degraded component, with NH.sub.3 and CO.sub.2 as hydrolysis end products. The enzyme uricase, which can be synthesized by many species of microorganisms, especially gram (-) bacteria, is responsible for this transformation. Given the large and diverse population of microorganisms in broiler litter, uric acid hydrolysis begins almost immediately following excretion. Protein and amino acid degradation, with NH.sub.3 as one end product, proceeds at a slower rate due to the greater complexity of these molecules.
Normally, uric acid is converted to allantoin by the enzyme uricase produced by gram (-) bacteria. See Equation 1. ##STR1## The allantoin is subsequently converted to allantoic acid, then to urea. Finally, the urea is converted to ammonia which results in an increased pH, creating an environment ideal for the formation of foot scabs and breast blisters.
In addition to ammonia, the proliferation of pathogenic microorganism is also a major problem. Caked and damp litter lead to increased pathogenic microbial growth further inhibiting performance of the birds and resulting in a human food safety risk. Spilled feed further compounds the problem since spilled feed and moisture lead to rapid proliferation of these microorganisms. A further problem is caused by excess water accumulating on the litter surface and increasing moisture content. This environment results in a high pathogenic microbial population in the litter.
Research has shown the damaging effects of pathogenic microorganisms on broiler feed conversion and growth. The greater the concentration of pathogens in the house, the greater the decrease in feed conversion and decrease in body weight gain. Since feed conversion and weight gain are significant portions of production efficiency, many growers that are trying to conserve costs by reusing litter are exacerbating the problem resulting in an even greater build-up of pathogenic microorganisms and higher losses.
The emerging market for broiler feet has recently focused attention on problems affecting poultry feet production and quality. One of the major defects reducing the economic value of feet are lesions or what are commonly called "foot scabs".
In addition to foot scabs, many birds also develop "breast blisters" or lesions on the breast. The widespread formation of breast blisters has a potentially devastating impact on the consumer poultry industry.
A number of environmental factors such as temperature, relative humidity and poor ventilation as well as nutritional factors, such as a biotin deficiency and excess salt levels in the diet, have been reported to affect the incidence of foot scabs and breast blisters. The result of the aforementioned environmental factors is wet, caked litter. These poor litter conditions lead to excess ammonia production and increased litter pH, which has now been found to play a primary role in the incidence of foot scabs and breast blisters.
Few treatments to improve litter quality have been reported. The prior art suggests utilizing acidifying compounds or absorbants in order to maintain proper litter pH, reduce ammonia and reduce the microbial load of the litter. However, due to the magnitude and diversity of microbial population in broiler litter and the continual introduction of new organisms in freshly excreted manure and from a variety of other sources, this approach is not always successful.
Further, disinfectants have been used by some in order to dilute the litter and maintain a proper pH. However, maintaining a lethal concentration of disinfectant is critical to its efficacy and to be truly effective, litter would have to be saturated with the disinfecting agent and thoroughly mixed to insure exposure to a lethal concentration of the disinfectant at a frequent interval. What normally results is merely surface applications which only temporarily slows microbial growth.
Others have attempted use of acidifying agents, such as phosphoric acid, aluminum sulfate (alum) or ferrous sulfate to reduce litter pH and thus the concentration of unionized or free ammonia. There are significant variations in effectiveness of this method. Much of this variation is due to the alkalinity or acid neutralizing capacity of litter which increases with litter age. As fecal material accumulates, salts of weak organic and inorganic acids and ammonia, which contribute to litter alkalinity, also increase. Thus, acidifying litter to a pH of 7.0, which is the point where essentially all litter ammonia is in the ionized form, only temporarily reduces ammonia volatilization.
Absorbants, such as clays, function primarily by providing negatively charged exchange sites to attract ammonium ions. In this process, more weakly bound ions such as hydrogen and sodium are replaced by ammonium ions, reducing the total concentration of ammonia in solution. The effectiveness of this ion exchange process in broiler litter is limited by several factors. One is the preference by most materials with ion exchange sites for ions with higher charges, such as calcium, magnesium and phosphorus. Since these ions are present in significant concentrations in broiler manure, absorbent effectiveness per unit volume in reducing ammonia volatilization is reduced and must be compensated for by higher application rates. The second factor is the need for contact between the ammonium ions in solution and the absorbent. Without thorough mixing, the effectiveness of any absorbent is minimal at best.
A primary method growers use for controlling ammonia levels is a properly designed housing structure complete with a ventilation system. Key components of the ventilation system are proper inlet location, air direction, air speed and volume of air. However, older facilities which do not have modern designs or sophisticated ventilation systems are looking at substantial expenses in order to remedy the situation. Also, the energy requirements to maintain a ventilation system are quite high. Further, higher levels of ventilation which lead to lower temperatures are not always tolerated well by growing chicks.
Various chemical treatments have also been described in the prior art but require constant addition to the litter and are quite expensive. Further, these chemical treatments are only able to reduce pH for very short periods of time.
The present inventors have been examining biological treatments for litter to reduce the incidence of foot scabs, breast lesions and illnesses caused by poor litter conditions. Based on extensive laboratory work and field trials, a reliable and cost effective biological litter treatment product has finally been developed. This invention acts as an effective component of a litter management program to reduce production losses due to poor litter quality.